[GRASS-dev] i.points, i.vpoints now use G_parser()

[Michael Barton]

> From: Glynn Clements <glynn at gclements.plus.com>
> Date: Wed, 28 Jun 2006 16:31:57 +0100
> To: Michael Barton <michael.barton at asu.edu>
> Cc: Hamish <hamish_nospam at yahoo.com>, <grass-dev at grass.itc.it>
> Subject: Re: [GRASS-dev] i.points, i.vpoints now use G_parser()
> 
> 
> Michael Barton wrote:
> 
>> So I should display a forward RMS and a backward RMS.
>> 
>> For each point, should I just display a single error distance or try to
>> display reverse for raster and forward for vector?
> 
> I suspect that you should probably display both.
> 
> AFAICT, either of the two points in a GCP pair can be misplaced just
> as easily. Also, when you are entering the control points, do you
> actually know whether they are going to be used for transforming a
> raster or a vector (or both)?
> 
> Maybe you could determine the size of the source and destination
> regions, and convert the absolute errors to a proportion of the
> region's size. That would allow you to sensibly compare forward and
> backward errors.

If I normalized them to percents (I'd better use a percent sign so as not to
confuse anyone), would this make sense to people? Or will people prefer to
see the distance in actual map units?

Michael

> 
> -- 
> Glynn Clements <glynn at gclements.plus.com>



__________________________________________
Michael Barton, Professor of Anthropology
School of Human Evolution & Social Change
Center for Social Dynamics and Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton